Radio navigation system



Aug. 26, 1952 T. J. GOLDAN RADIofNAvIGATIoN SYSTEM Filed March 29, Y194'? r www A TTORNFY Patented Aug. 26, i952 This.inventionrelates to a radiof navigation tion "of a 'object ,stationr` with reference to two fnC Vthe previo :energy:` standing wavej patterns are usually es-I -tablishedfbetween the'two iixedstations'. A re-V sceiverlocated in an objectstation, as for example sa mohileivehicle oraircr'aft, is tuned to the ire-.j4 iquency" of transmission and' detects the pattern minimum and maximumandthrough` suitablev liner andrelays actuates `a mechanical countexn if allylprovide means for measuring the tim arriyal'of signalfpulses"` received from sev- Y eainxd stations; lthe transmission of the pulses from` the Viixed stations usually being synchronizedjin' a [predetermined manner. However,

these; 'systems- ,have 'usually` Yrequired. elaborate melasurmngiapparatus such asoscillographs for measuring discrete Lquantities, or else thequality of "the .m asiirements is variable and not precise enough.;

object of the presentf invention is to proe vide an improved radio navigation system.

Another. object ofxthis invention is to provide an'improved method of signal transmission from fixeldstations for determining the position of an `lilnjother object of the invention is to provide new and' improved methods and apparatus for determining the 'location of objects with a single and inexpensive device, particularly objects having an electromagnetic 1 receiver.

Inaccordancewith thepresent invention two stations arefprvided at xed positions along a given 'courses which transmit electrical signals having. varying characteristics in synchronism i"'asby=`proviiing oontrolby one station over the Aothersand means areprovided at an object orfln'virlg` station 4located 'along this course for translating the variable characteristic electrical signa-lsarriving simultaneously thereat from said flxedstations, andthereby actuate a simple indioator for indicating the position of the object with respect to the fixed stations. V`@The above mentioned `and other features of this invention will become more apparent, and ntio'nitself, though notfnecessarily desaid featres and` objects, will be best urfdsrsedociby referencer@ the following de'- ns 'and particularly to Ysystems Where-14 vion translates related'radiant. ran'smitted' byf'th'ej ihedstations .di frQm` mere' bearing determinauslsystems fofV this type, radiant` wherein bothstations `transmit frequency inodu' NIT-EDISTATES PATENT i OFF 2,6% 684 e Ramo NAVIGATION SYSTEM yTheodore GoldanLNeW York, N. Y., assigner to Federal Telephone and Radio Corporation, New York, N Y., a corporationlofi Delaware piiiicanon Marsh 29, 1947`,lseria 1marsans;

fj 7 "12"Cl ainis. (Cl. '1 :A 1` A system: royiding means''for locating the' 'posiz howfa'ccumulatedf distance. Other syslated. Waves] Y. In Figi a master transmittingstation is show comprising a pulse `generator I, having a pulse` recurrence.;` frequency substantially twicef the tirnejit .takes j a AAradiant` energy wave` totravelj from* theimaster to 'la lslavetaton; 'Challenging pulses from.generatorV I `fare appliedthrouglfi' conf-` nection `2 'to `radiant energy' transmitter3` ifor'f'` transmissionto the slavestation. Simultaneous- 1v `the pulses fromeeneratorlere; delayed `irl; a" dlay'line `4j for alperiod sucient'tolperrnit'th f trigger pulse j to reach the sl ave station dent withjtheibeginning',of'the s layestati n."A spense, transmission. The "delayedjpulses 1 r, A next` passed tothe `circuitj 51er. producing fsa` toothwaves'having'a duration correspOndllgjtof they 1 remaining time interval before Lthe .next challenging pulse. The sawtooth signalfis'then,

cillator circuit] foi producing frequencylfmodu lated.` signals" of increasing .frequency asfthe sa tooth voltageincreases along itssloping edge.." This increaseof frequency.signalnis Athen' passati@` 1 .to ,transmitter `3` and. ,transmitted to' .the slave station. Thus from` thetiine immediately 1afte'jrff the transmission of the challenging pulsefroinl generator `I Vthere Vis transmitted from the `master station awavemodulated withV a gradually in,-r

creasing -frequency until the pulse originally1 transmitted `fromthe master station travels `to the slave stationzand back again to th-; .r na s te rLA station, .at which time anothenpulse is,` trans-, mitte@ ,andrtheyle isreread ontinuouslr. .a

-I t -is desirable, ,-,butenot necessary, `that the; transmitter antennae for the master and slavef stations be directivetoward each othenhoth ffor economy-in power and in order that anobject@- station will better know when it is on theiixed path-between the master and slave stations. y The slave station is adapted lto rcce1vethe challenging puISestranSmitted fromthelmastei st ,ationl on-a frequency FM in thef receiver 81..,

. Slectefdypulsesmay then be passed`,f`i"f. desired@ througl'a shaping circuit 9 to 'improve'their shape, and thence to a transmitter l0 operating ter station. At that time, the summation freon a frequency FS different from that FM of quency willv be a function of the elapsed time transmitter 3. from the transmission of the main pulse from Wave forms showing these signals are illusthe master station, and the time of its reception trated in Figure 2. The signals from the mas- 5 at the object station, and consequently a functer station comprise a main pulse M which is tion of the distance between the master station the one transmitted from generator l through and the object station. The frequency meter I1, line -2 directly gto =.transmitter 3; followedwby a@ therefore; indicates increasingedistanegrom the frequencylmodlated'i'wave Which.,'fgra'dually"in master s'tationiirectly withliiicreasedgfzeguency. creases in frequency until just before the pulse 10 While I have described above the principles of M is again transmitted. Starting at one half; y.Iriyg invention in connection with specific appathe time period between the main pulses arethe `I'itllsi.and particular mOdCatUnS hBI'eOf it 1S pulses transmitted from the slave-station fSi- Y Vto#beclearlyunclerstood that this description is i319 madeonly by wayrofexample and not as a limitaits duration as described hereafter. Y j f1.5, ltQlQPthe.scopegofimy invention. Furthermore, if the pulses.fshowsubstantial; 1 I claim; duration it may be desirable to insert inthe cir. 1 In a radio IlaVigatOn System, means fOr decuit between shaper 9 and the"transmitter' |11;` j terming Y1Jhe`1-0c2`ffii0r1 0f an Object station along the circuitof Figure 3. The signais fromgaare ff `a,iiiihiam?.lwxlnfiilly de trmined by twv relathen passed through a sgwtooth generator Il, 20 tively fixed stations comprising means at one of insina """to, the p corresponding c'iruitpf they reference. and. .at a predetermined masterv station, but operating in "sucht manfrier afteij tQlfanSmtlSgp-Ihailngfleqll?cy assi-.0.. produce gradually-f decreasin g'`.fi'uer icy aQterStQYayingnilenire@ signasinoiateaonine-single Escarrier-g f 25. thesecendffsad. #estati Firtherinc'ire',` 'if found desirable the carrier, thecqeptoffsad mayibe modulated lwith .arseparate amplitude `:.or SubSlIitilly' at t h iicLo'fI iifiy 'encylino'dulated,wavevaryingin ffrequency time signals having a 'frequency' 'Such isf .an. bvious modification -of previously ydescribed. 30, 111.g- ,how to fthe object `-s'tafi 1i1j..-tl'iisinf'i' chi-des means'for receiving the above. des cribe`1 transmission `:and may comprise v,separate receiv- Lan'df I'Stuned vtofrequencies.ofFM and otivel'y. .Theoutputs ofreceivers |4 an `d |'5 :"35 .sai d,resu1tant injtermsjofdista arecoibinedin f1i-1`ff1leicircuitf lwhich'is so arf..V 2'... AadOJnyigatiQn systemcomprsing ea rangedasto be,normallylb1ocked,` and tri ggered fordetermining thejlocation.Qfjan henfsignals.,arereceived.simultaneously with respecttoagmaster' accaesafV i x ul'atdl signals-i 4i '-A lradicnavigationY system comprising means for determining th'e'position of an object station with respect'to 'a master and slave fstation, vsaid.

master. station comprisingfmeans forltransmitting a triggerpulse, Vmeans for transmitting said trig-` ger pulseuto said slave stationfmeans foridelaying saidtrigger pulsefor a predetermined time'interval, means responsive to said delayed fpulseiforV producingsignals vfrequency modulated in a given- Y direction and ofwa given duration," means for transmitting' said vfrequency modulated .signalsf saidv slave station comprising means for receiving said trigger- `pulsepmeans `for transmittinga# response signal ofi a lgiven duration, said: object station comprisingmeansffor receiving said fre-` quency modulated lsign'als `and said response sig- V nal, means responsive tothe simultan'eousarrival-f7v for determining the position of an' object station Withrespect toa masterv andslave station, said master station comprising means for transmitting trigger pulses -having a `predetermined pulse recurrent frequency, means for delayingsad trigger pulses for alpredetermined time interval,

means responsive to said delayed pulses for producing frequency modulated signals of increasing frequency and of a duration dependent upon the,

time `interval betweentrigger pulses, and means forl transmitting said frequency "modulated signais, 'said' slave station -comprising means for receiving said trigger pulses, and Vmeans for transmitting a response-pulse of a' give'nfduration, said object station comprisingmeansfor receiving said frequency modulated signal and said response pulse, 4'means responsive to 43h?. simultaneous reception of said frequency modulated signals and said response pulse for translating said received energy, an indicator responsive to said translated energy for indicating the position of said object station. f

6. A radio navigation system for determining the location of an object station with respect to a master and slave station,`said master station comprising means for producing a trigger pulse to actuate said slave station followed by frequency modulated radiant energy signals, said slave station station comprising means for receiving said frequency modulated signals and said response signal, means for demodulating said last named frequency modulated and response signals received simultaneously by said receiving meanameans for applying said demodulated signals to an indicator, said indicator comprising means for translating said demodulated signals for indicating said object station location.

7. A radio navigation system for determining the location of an object station with respect to a master and slave station, said master station comprising means for producing a trigger pulse to actuate said slave station and means for transmitting at a predetermined time interval after the transmission of said trigger pulse radiant energy signals frequency modulated in a given direction, said slave station comprising means for transmitting a single pulse of radiant energy of comprising means for transmitting aV response signal of predetermined duration upon the reception of said trigger pulse, said object Yloy said separate receivers, means responsive t" said combined energy for translatingfsaidjlas't namedenergy `and for providing an'indicationof a givenr frequency `:upon there'ception of said trigger pulse, said `object station Vcomprising means l'for receiving said ,frequencymodulatedfV signals and said given frequency pulse,l means for `demodulating said ulast" namedffsignalslfand pulses received simultaneously by said receiving means, means for applying ysaid ldemodulatedenergy to anindicator, said indicator comprising means for translating said demodulated energy for indicating said object station location;

f8. A radio navigation system for determinin'gf theposition of an object station With res'peci'it'ov i a master and slave station, said masterstation comprising a pulse generator, `a radiant energy* transmitter, a. delaycircuit, a saw-tooth wave l generator, means forlapplying generated pulses to `saidtrans'mitter. for transmitting "a triggeril pulseto said slave station; meansfor applying said pulse to said delay circuit for delaying'said pulse for a predetermined time interval, means for applying said delayed pulsefora predeter mined time interval, means for applying said `de-i` layed .pulse to said saw-tooth generator forfpro"` ducing a saW-toothwave of a given duration,Vy a signal loscillator. .means comprising `a reactance modulator lfor applying `said saw-tooth Waveto said signal oscillator whereby'` frequency modu lated' Waves of increasing frequencyeciorrespond'; ing to the amplitude of said saw-tooth wave are'l produced, means'for transmitting said frequency` modulated Waves, said slave stationV comprising*- means for receiving said trigger pulse,means-`fo`r` *l shaping said pulse, means responsive to?` said shaped pulse for transmitting a given pulse,`-said object station comprising separate receivers "for-f` receivinglsaid given frequencyA pulse and *said frequency modulated waves, means for combining the energy of said received pulse and Wavesicom# prising a mixer circuit responsive only to said-vA-`4 receivedfenergy when received simultaneously the position of said object station.

9. A radio navigation system for determinin the position of an object station with respect to a master and slave station, said master station comprising a pulse generator, for producing pulses of a given pulse recurrence frequency, a radiant energy transmitter,` a delay circuit, means for applying said pulses to said transmitter for transmitting a trigger pulse to said slave station, means for applying said pulse to said delay circuit for delaying said pulse for a time interval, sucient to permit the trigger pulse to reach the slave station, means: responsive to said delayed pulse for producing a saw-tooth Wave of a period corresponding to the remaining time interval before the succeeding trigger pulse a signal oscillator, means including a reactance modulator for applying said saw-tooth Wave a reactance modulator lto said signal oscillator whereby frequency modulated waves of increasing frequency corresponding to the amplitude of said saw-tooth Wave are produced, means for transmitting said frequency modulated waves. said slave station comprising means for receiving said trigger pulse, means for shaping said pulse, means responsive to said shaped pulse for transmitting pulse of given frequency said object station comprising separate receivers for receiving said given frequency pulse and said frequency modulated Waves, means for combining said last named signals comprising a mixer circuit responsive only to said signals or received simul- 

